Designation: C1738/C1738M − 14
Standard Practice for
High-Shear Mixing of Hydraulic Cement Pastes1
This standard is issued under the fixed designation C1738/C1738M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 mixing, high-shear, v—of pastes, the process of blending dry and liquid materials in a container using blades rotating
axially at speeds at or above 420 rad/s [4000 rpm].
1. Scope
1.1 This practice covers the high-shear mixing of hydraulic
cement pastes.
1.2 The values stated in SI units or inch-pound units are to
be regarded as the standard. Within the text, the inch-pound
units are shown in brackets. The values stated in each system
are not exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two
systems may result in nonconformance with the standard.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
4. Summary of Practice
4.1 The practice describes the mixing of hydraulic cement
paste in a high-shear mixer with a cooling jacket or other
method to control the temperature of the paste. This procedure
is derived from the ANSI/API standard and the following
reports:
(1) R. Helmuth, L.M. Hills, D.A. Whiting, S. Bhattacharja,
Abnormal Concrete Performance in the Presence of
Admixtures, RP333, Portland Cement Association, Skokie,
Illinois, USA, 1995, 92 pages and
(2) C. F. Ferraris, Measurement of the rheological properties of cement paste: a New Approach, Int. RILEM Conf.
—The role of Admixtures in High Performance Concrete, ed.
by J.G. Cabrera and R. Rivera-Villareal, Monterrey (Mexico),
March 1999. pp. 333-342, or
(3) C. Ferraris, K. Obla, R. Hill, The influence of mineral
admixtures on the rheology of cement paste and concrete,
Cement and Concrete Research Vol. 31/2, pp. 245-255 (2001).
2. Referenced Documents
2.1 ASTM Standards:2
C219 Terminology Relating to Hydraulic Cement
C305 Practice for Mechanical Mixing of Hydraulic Cement
Pastes and Mortars of Plastic Consistency
C511 Specification for Mixing Rooms, Moist Cabinets,
Moist Rooms, and Water Storage Tanks Used in the
Testing of Hydraulic Cements and Concretes
C1005 Specification for Reference Masses and Devices for
Determining Mass and Volume for Use in the Physical
Testing of Hydraulic Cements
2.2 Non-ASTM Standard:3
ANSI/API Recommended Practice 10B-2 (formerly 10B)—
Recommended Practice for Testing Well Cementsǁ
5. Significance and Use
5.1 This practice is useful in laboratory research on rheology of hydraulic cement systems as it has been shown to
provide a paste with rheological properties similar to those
obtained in a concrete from which the aggregate had been
removed.4 Mixing of paste using C305 is not satisfactory as the
paste is not thoroughly mixed, due to the absence of sand. In
this practice the shear imparted to the cement paste is significantly higher than in C305 and therefore it is known as
high-shear mixing.
3. Terminology
3.1 Definitions—For definitions of terms used in this
specification, refer to Terminology C219.
6. Apparatus
1
This practice is under the jurisdiction of ASTM Committee C01 on Cement and
is the direct responsibility of Subcommittee C01.22 on Workability.
Current edition approved April 1, 2014. Published May 2014. Originally
approved in 2011. Last previous edition approved in 2013 as C1738/C1738M - 13.
DOI:10.1520/C1738_C1738M-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
6.1 Mixer—Composed of an electrical motor, a mixing
container and a tachometer with the motor speed controlled
automatically (rheostat adjustment of speed will not be acceptable). The blades are attached to the bottom of the container
4
R. Helmuth, L.M. Hills, D.A. Whiting, S. Bhattacharja, Abnormal Concrete
Performance in the Presence of Admixtures, RP333, Portland Cement Association,
Skokie, Illinois, USA, 1995, 92 pages.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1738/C1738M − 14
7.2 The cooling unit flow rate and temperature shall be
adjusted so that the temperature of the cement paste, after
mixing, is within the specified range (see Note 4).
and rotate axially. The power of the motor shall be sufficient to
ensure that the speeds of the mixer loaded with 500.0 g [1.1 lb]
of cement and water shall maintain a preset rotational speed at
420 rad/s [4000 rpm] and 1047 rad/s [10 000 rpm]. The speed
shall be maintained within 5 % of the preset speeds.
NOTE 4—Typically water temperatures of 15 6 2°C [59 6 4°F] are
required for a cement paste temperature of 21 6 2 °C [70 6 4°F]. Higher
or lower temperature water could be used to simulate hot or cold weather
concrete. The references4,6 provide a more detailed explanation on how to
select the cooling temperature.
NOTE 1—A variable speed mixer capable of controlling the speed by a
feedback loop within a range of 0 rad/s [0 rpm] to 1360 rad/s [13 000 rpm]
is recommended. A mixer with a minimum of two speeds (420 rad/s [4000
rpm] and 1047 rad/s [10 000 rpm] loaded) preset either by the operator or
by the manufacturer is acceptable.
8. Materials and Proportioning
6.2 Cooling Unit—A water bath with an outside circulating
option, capable of controlling the temperature to 61°C [61°F]
for the specified temperature range of 5-50°C [40-120°F] over
the duration of the test.
8.1 The materials and their proportions and quantities shall
conform to the requirements contained in the particular method
for which the paste is being prepared.
6.3 Mixing Container with the Blade Assembly5—A 1-L [1
qt] container, lid and blade specifically designed for use with
the mixer motor. The blade assembly shall be constructed in
such a manner that the blade can be removed for weighing and
changing. The blade shall be weighed initially and then
periodically, replaced with a new blade when a 10 % mass loss
has occurred. Replace the blade if obvious blade deformation
has occurred. If the mix temperature is to be controlled by a
separate cooling unit, the container shall also be equipped with
a cooling system (see Note 2) that can be connected to the
cooling unit.
9. Procedure
9.1 Place the mixing container on the mixer and if
applicable, connect the hoses to the cooling unit.
9.2 If using an external cooling unit, adjust the temperature
to the desired temperature and turn on the water supply to the
jacketed bottom of the mixing container.
9.3 If paste temperature is to be controlled by the mix water,
prepare required quantity of water, at the desired temperature
and maintain until needed.
9.4 Loading of the Mixer:
9.4.1 Add the specified quantity of dry cementitious materials in their correct proportions to the cementitious feeder.
9.4.2 Add the correct amount of water to the mixing
container, cover with lid and begin mixing at the first preset
speed (420 rad/s [4000 rpm]) allowing water temperature to
stabilize throughout.
9.4.3 Turn off mixer and remove lid. Insert thermometer
into the water being careful not to let the tip of the thermometer
touch the mixing container. If the measured temperature is not
correct for the desired paste temperature, perform the
following, as applicable.
9.4.3.1 If using an external cooling unit, place lid on the
mixing container and continue mixing at the first preset speed
(420 rad/s [4000 rpm]), periodically checking the temperature,
as previously described, until the water has reached the desired
temperature. Adjust the cooling unit temperature, if needed.
9.4.3.2 If using mix water for temperature control, completely empty water from mixing container and replace with
the required quantity of water that has been adjusted for
temperature. Repeat 9.4.2 and 9.4.3 above, as needed, until the
water has reached the desired temperature.
9.4.4 As soon as the water reaches the desired temperature,
start mixing at the first preset speed (420 rad/s [4000 rpm]) and
using the cementitious feeder, begin adding the dry materials to
the mixing container. The feeding of dry materials should be
uniform and completed in approximately 60 s.
NOTE 2—The cooling system could be either an integral part of the base
of the container or a coil wrapped around the container.
6.4 Thermometers—A partial immersion thermometer readable 0.5°C [1°F] and accurate to 60.5°C [6 1°F] when tested
at 23°C [73°F] with a the range of 5-50°C [40-120°F].
6.5 Cementitious Feeding System—A feeding system, capable of adding the total quantity of cementitious material into
the mixing container, within 60 s (see Note 3).
NOTE 3—A vibratory feeder or a lid mounted funnel is suitable for this
purpose.
6.6 Timing Device—Stop watch or other suitable timing
device accurate to 61 s when tested over a one-minute
interval.
6.7 Top-Pan Balance—Complying with Specification
C1005 having a capacity of at least of 1 kg [2 lb] and
readability and accuracy of 0.01 g [2·10-5 lb].
6.8 Scraper—The scraper shall consist of a semi rigid
rubber blade attached to a handle about 150 mm [6 in.] long.
The blade shall be about 75 mm [3 in.] long, 50 mm [2 in.]
wide, and tapered to a thin edge about 2 mm [0.08 in.] thick.
7. Temperature and Humidity
7.1 The temperature and humidity of the mixing room shall
conform to the requirements of Specification C511.
9.5 Initial Mixing:
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The sole source of supply of the container and blades known to the committee
at this time is (Specialty Containers manufactured by Waring Products, Torrington
CT (http://www.waringproducts.com/lab)). If you are aware of alternative suppliers,
please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical
committee, which you may attend. The SS510C One Liter Cool Base Container with
the blade assembly is considered to conform to these requirements
6
Taylor P.C., Johansen V.C., Graf L. A., Kozikowski R. L., Zemajtis J. Z.,
Ferraris C. F., “Identifying Incompatible Combinations of Concrete Materials;
Volume I & II” FHWA report # FHWA-HRT-06-080, 2006 (http://
www.fhwa.dot.gov/pavement/concrete/pubs/06079/ and http://www.fhwa.dot.gov/
pavement/concrete/pubs/06080/index.cfm)
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C1738/C1738M − 14
9.5.1 As soon as the dry material addition is complete,
attach the lid to the mixing container and switch to the second
preset speed (1047 rad/s [10 000 rpm]).
9.5.2 After 30 s of mixing, stop the mixer
9.5.3 Rest Period—Allow the paste to stand in the mixer for
150 s. During the initial 15 s of the rest period, remove the lid
and using the scraper, scrape down the inside of the mixing
container to incorporate any dry material into the paste that
may be left on the sides of the container. Measure the
temperature of the paste without touching the bottom of the
mixing container. Record the temperature. Replace lid on
mixing container for the duration of the rest period.
NOTE 5—Other mixing speeds could be used to simulate variations in
mixing of concrete.4
9.7 As soon as the final mixing is complete, stop the mixer
and measure the temperature of the paste by moving a
thermometer in and around the paste without touching the
bottom of the mixing container. Record the temperature.
9.8 The paste is now ready to be used, as required.
10. Keywords
10.1 cement paste; high-shear mixing; hydraulic cement;
rheology
9.6 Final Mixing—Immediately following the rest period,
start the mixer at the second preset speed (1047 rad/s [10 000
rpm]). Mix the paste at this speed for an additional 30 s (see
Note 5).
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